Hostname: page-component-848d4c4894-r5zm4 Total loading time: 0 Render date: 2024-06-20T20:17:11.702Z Has data issue: false hasContentIssue false

Reactions of herring schools to the sound field of a survey vessel

Published online by Cambridge University Press:  15 January 1996

Ole Arve Misund
Institute of Marine Research, PO Box 1870, N-5024 Bergen, Norway
Jan Tore Øvredal
Institute of Marine Research, PO Box 1870, N-5024 Bergen, Norway
Magnus Thor Hafsteinsson
Department of Fisheries and Marine Biology, University of Bergen, N-5020 Bergen, Norway
Get access


The underwater sound of R/V "Johan Hjort" as a function of aspect angle has been mapped by cruising along parallel transects at various distances from the recording unit. At frequencies over 125 Hz there was a minimum in front of the vessel, and lobes of higher intensity on both sides. About 20% of the herring schools recorded during a survey in the North Sea seemed to react to the survey vessel. The distance at which the schools reacted varied from about 25 m and up to about 1000 m in front of the vessel. Within a sector of 20° on each side of the path of the vessel, the fraction of schools reacting increased to about 50%. Most of the schools that reacted seem to be herded in front of the vessel. This reaction pattern may indicate either that the schools reacted to the higher sound intensity to the side of the vessel or that the pattern occurred because of a "pursuit effect". Despite the apparent herding, more than 40% of the schools in front of the vessel were not recorded by the echo sounder. It is therefore argued that horizontal avoidance close to the vessel may have caused an underestimation of the biomass of herring of about 20%.

Research Article
© IFREMER-Gauthier-Villars, 1996

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)